Optical monitoring of products of the tobacco-processing industry

ABSTRACT

Method of optically monitoring a tobacco-processing industry product with a gradient-index lens and device for optically monitoring tobacco-processing industry products. The device includes an image-recording device comprising at least one gradient-index lens. A method of optically monitoring a product in a machine for making or processing tobacco-processing industry products is also provided. The method includes arranging a device for optical monitoring of the product on the machine for making or processing tobacco-processing industry products. The device for optically monitoring includes at least one gradient-index lens. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of International Patent Application No. PCT/EP2005/007223 filed Jul. 5, 2005, and claims priority under 35 U.S.C. §119 of German Patent Application No. DE 10 2004 040 912.9, filed on Aug. 23, 2004. Moreover, the disclosure of International Patent Application No. PCT/EP2005/007223 is expressly incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the optical monitoring of products of the tobacco-processing industry and a device for the optical monitoring of products of this type comprising an image-recording device.

Within the scope of this invention, products of the tobacco-processing industry mean, in particular, rod-shaped and strip-shaped products or objects such as cigarettes, filter rods, multisegment filter rods, cigarette paper or tipping paper, and stamp imprints on paper webs or glue application on paper webs. In optical monitoring, quality features on the products of the tobacco-processing industry are generally detected, such as holes, lengths, an object identification, stamp, glue application, smudge dimensions, the presence of filter elements, damage, and the like.

2. Discussion of Background Information

In optical monitoring, line cameras or matrix cameras are generally used which, as a rule, are equipped with expensive large lenses due to the requirements of imaging and resolution quality. A considerable distance from the measuring object to the camera is also necessary in order to, for example, view the entire cigarette length without distortion and impairment of its sharpness. At some locations of a tobacco-processing machine, such as, e.g., a filter tipping machine, the optical path has to be bent several times with mirrors. In addition, at many points in a filter tipping machine, optical monitoring cannot be provided due to geometric conditions of the machine.

The illumination of the objects or products of the tobacco-processing industry which are to be measured is realized with separate light sources that must have high light intensities because of the large distance from the object. It is also known, for example, to bring the light to the measuring object by fiber optic cables (which utilize losses of intensity). In such an arrangement, however, the probability is great that particles flying about, such as, e.g., tobacco dust, will interfere with the optical monitoring and can produce false evaluations. Such conditions can be reduced only by employing expensive measures due to the large distance from the monitoring devices to the objects.

SUMMARY OF THE INVENTION

The present invention aims to address one or more of these problems and relates to a compact device for the optical monitoring of products of the tobacco-processing industry. The invention also aims to fundamentally reduce cross interferences in the optical monitoring of products of this type.

According to one aspect of the invention, a gradient-index lens for the optical monitoring of products of the tobacco-processing industry is utilized.

Within the scope of the invention, a gradient-index lens is a transparent element that produces a lens effect through a continuous variation of the refractive index. Instead of surfaces in part of complex shape (as are utilized in conventional lenses), the light beams of the gradient-index lens preferably enter in plane surfaces. The light beams are continuously deflected in the gradient-index lens and finally focused in a focal point. The refraction index is thus preferably varied crosswise to the optical axis. Gradient-index lenses can be realized in a particularly compact manner and, in particular, can have a very small diameter. Furthermore, the lens length can be variably adjusted and above all the focal length as well as the working distance can be brought very close to the ends of the gradient-index lenses. For example, through a suitable selection of the lens length, the image plane can lie directly on the flat surface of the lens so that light sources can be adhered directly to the lens. In particular, it is also possible to embody or to arrange the focal length to the product to be optically monitored very close to the preferably flat surface of the gradient-index lens so that, due to the close proximity of the lens to the product to be monitored, only a few particles can interfere with the monitoring, i.e., owing to the fact that there is space for only a few particles in the distance between the lens and the product to be measured or monitored.

The invention can be particularly effective when a plurality of gradient-index lenses are used and/or arranged next to one another, in particular, are arranged in at least one row. In this case, rod-shaped and strip-shaped objects can be easily monitored for quality and other properties. Moreover, if a gradient-index lens is used to illuminate the products of the tobacco-processing industry, the part of the optical monitoring device which provides the illumination of the products can also be embodied in a compact manner. A particularly effective illumination is given if a plurality of gradient-index lenses are arranged next to one another, in particular, in one row and are used for illumination.

The invention also provides for a device for the optical monitoring of products of the tobacco-processing industry comprising an image-recording device, whereby the image-recording device comprises at least one gradient-index lens. A device of this type can be realized in a very space-saving manner due to the use of a very compact gradient-index lens, as well as due to the focal lengths or distances of the respective ends of the gradient-index lens to the focal points which can be adjusted to be very short. Preferably, the image-recording device comprises a plurality of gradient-index lenses arranged next to one another, in particular, in a row. Utilizing this arrangement, rod-shaped and strip-shaped objects or products can be monitored very effectively.

If the image-recording device also comprises a line of photo diodes or a CCD (Charged-Coupled Device) line, a simple as well as space-saving arrangement for taking or recording of the images of the objects or the products of the tobacco-processing industry is possible. A CCD line is known per se. However, the invention can utilize special CCDs, in particular, in which half of the elements provided in the CCD converts an image focused on the surface point-by-point into intensity-dependent charge amounts, while the other half is used to save and read out the information. In this respect, the CCDs are used as image sensors.

Preferably, the image-recording device also comprises a device for comparing the recorded images to predetermined images. Through this arrangement, an efficient optical monitoring of the products is possible. For example, in monitoring filters or filter cigarettes, an image of a correct filter or a correct filter cigarette can be saved and this image can be compared to the recorded image of the filter or filter cigarette to be monitored. It is also possible to monitor multisegment filters in a particularly efficient manner using the invention. If, e.g., too great a difference occurs in the intensity distribution, the product or products monitored can be eliminated from further processing. The device for comparing the recorded image to one or more predetermined images can preferably be a computer that stores the predetermined image or images in a storage device, and can perform the function of comparing this image with the recorded images. Such a system can also produce or generate a control signal that represents a correct product or a product to be rejected. Such signals can be utilized to operate or control various devices of the machine.

If an illuminating device with a light source and at least one gradient-index lens guiding a light from the light source to the product to be monitored are both provided, this can also be realized in a very space-saving manner. The illumination can be particularly effective if a plurality of gradient-index lenses arranged next to one another, in particular, in a row.

Within the scope of this invention, an arrangement of such devices next to one another, particularly in a row, also means the arrangement can have the form of an array (see e.g., FIG. 3). The device according to the invention can be used in a particularly effective manner if the focus of the gradient-index lens is arranged at the end or in the direct proximity of the end of the gradient-index lens. Through such an arrangement, measurement inaccuracies or faulty evaluations due to the existence of particles such as tobacco dust flying about can be avoided as far as possible.

The invention also provides for a machine of the tobacco-processing industry that preferably comprises at least one device according to the invention for the optical monitoring of products of the tobacco-processing industry.

In a particularly preferred embodiment, in the machine of the tobacco-processing industry can produce products, in particular, filter rods or cigarettes, which are guided in a transverse axial manner past the plurality of gradient-index lenses arranged next to one another.

The invention provides a method including optically monitoring a tobacco-processing industry product with a gradient-index lens. The gradient-index lens may be arranged on a machine for making a tobacco product. The gradient-index lens may comprise a plurality of gradient-index lenses arranged at least one of next to one another and in at least one row. The plurality of gradient-index lenses may be structured and arranged to illuminate a surface of the tobacco-processing industry product. The gradient-index lens may be structured and arranged to illuminate a surface of the tobacco-processing industry product. The gradient-index lens may further comprise a plurality of other gradient-index lenses arranged at least one of next to one another and in at least one row. The plurality of other gradient-index lenses may be structured and arranged to illuminate a surface of the tobacco-processing industry product.

The invention also provides for a device for optically monitoring tobacco-processing industry products, wherein the device comprises an image-recording device comprising at least one gradient-index lens. The at least one gradient-index lens may be arranged on a machine for making a tobacco product. The at least one gradient-index lens may comprise a plurality of gradient-index lenses arranged at least one of next to one another and in a row. The image-recording device may further comprise one of a line of photodiodes and a CCD line. The image-recording device may comprise at least one of a photodiode and a CCD. The image-recording device may further comprise a device for comparing a recorded image with at least one predetermined image. The device may further comprise a device for comparing a recorded image recorded by the image-recording recording device with at least one predetermined image. The device may further comprise an illumination device for illuminating an object surface. The illumination device may illuminate the object surface using a light source and at least one gradient-index index lens guiding light from the light source to the object surface. The image-recording device may record an image of the object surface that is illuminated by the illumination device. The device may further comprise a plurality of gradient-index lenses arranged at least one of next to one another and in a row. The device may further comprise a plurality of other gradient-index lenses arranged at least one of next to one another and in a row to illuminate an object's surface. The image-recording device may comprise at least one gradient-index lens, and a focus of the at least one gradient-index lens may be arranged at or on an object surface. The focus may be arranged one of at one end of the at least one gradient-index lens and in an immediate proximity of one end of the at least one gradient-index lens.

The invention also provides for a machine for making tobacco-processing industry products, wherein the machine includes a device for optically monitoring products of the tobacco-processing industry with a gradient-index lens. The tobacco-processing industry products may comprise one of filter rods and cigarettes. The tobacco-processing industry products may be guided in a transverse axial manner past a device for optical monitoring of products. The at least one gradient-index lens may comprise a plurality of gradient-index lenses arranged at least one of next to one another and in at least one row.

The invention also provides for a method of optically monitoring a product in a machine for making or processing tobacco-processing industry products, wherein the method comprises arranging a device for optical monitoring of the product on the machine for making or processing tobacco-processing industry products, wherein the device for optical monitoring comprises at least one gradient-index lens.

The invention also provides for a gradient-index lens structured and arranged to optically monitor a tobacco-processing industry product

Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:

FIG. 1 shows a diagrammatic side view of a filter tipping machine;

FIG. 2 shows a diagrammatic representation of the mode of operation of a gradient-index lens;

FIG. 3 shows a diagrammatic open representation of a gradient-index lens arrangement; and

FIG. 4 shows a diagrammatic sectional representation through a filter rod and two monitoring devices according to the invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.

FIG. 1 shows in a diagrammatic side view a filter tipping machine and illustrates its essential parts. The filter tipping machine, e.g., of the MAX type (made by the assignee), utilizes a transfer drum 2, on which cigarettes of double unit length produced by a cigarette-making machine were transferred. Next, the cigarette rods of double unit length are fed to a cut tobacco rod cutter drum 3 which cuts the cut tobacco rods into two cut tobacco rods of single unit length. After the cut tobacco rod has been cut, the cut tobacco rods are fed to a spreader drum 4, by way of which the cut tobacco rods are spread apart such that there is space in between them for filter elements. The cut tobacco rods spread apart in this manner are then fed to a feed drum 5. Filter elements are also fed to the feed drum or transport drum 5 in the illustrated machine. These filter elements are inserted between the cut tobacco rods on the feed drum 5 into the corresponding seats of the feed drum 5. To this end, firstly (not shown in FIG. 1), the filter elements are removed from a filter element store by way of a cutter drum, removal drum, and a cutter drum 6. Regarding the removal of filter elements from a filter element store, reference is made to DE 25 05 998 C2 of (which U.S. Pat. No. 4,020,973 is a U.S. patent family member). These filter elements can be, e.g., multiple filter elements that have corresponding filter components (not shown) in 16-fold unit length.

First, they are cut twice on the cutter drum 6 by way of circular knife 10 into multifilter segments of 4-fold unit length. These multifilter segments are staggered in the staggering drum 7 in order to then align them in a pusher and cutter drum 8; first in a transverse axially aligned manner and then to cut them again with a circular knife 10 into multisegment filter sections of double unit length. Subsequently, the filter elements are again aligned on the pusher and cutter drum 8 in order to be cut again by a circular knife 10 into multifilter segments of single unit length. These are then transferred to a pusher drum 11 and then transferred to the feed drum 5 by way of an accelerating drum 12. In this way, the multisegment filter elements of single unit length abut the cut tobacco rods on the inside. Another filter element of 12-fold unit length is removed from a filter store in a known manner by way of a cutter drum or cutter/removal drum 15 (as above, see DE 25 05 998 C2 and U.S. Pat. No. 4,020,973). These filter sections are cut twice by circular knife 10 on the cutter drum 15, in order to be transferred to a staggering drum 16. After they have been staggered, these filter elements are then transferred to a pusher and cutter drum 17 where they are aligned in a transverse axially aligned manner and cut twice, so that filter elements of single unit length are produced. Subsequently, the filter elements of single unit length are staggered in a staggering drum 18 in order to be transferred to a pusher drum 19 in which they are pushed together in a longitudinal axially aligned manner. Another accelerating drum 13 is used to insert the filter elements into the center of the respective seats. In this exemplary embodiment, firstly the latter filter elements of single unit length are inserted into the center of the seats of the feed drum 5, in order then to arrange the other filter elements of single unit length outside around them, and subsequently to arrange the respective cut tobacco rods at the very outside.

The cut tobacco rod/filter element/cut tobacco rod groups or cigarette/filter/cigarette groups thus assembled are then fed to a transfer drum 21. At this point, a first optical monitoring is carried out. A first monitoring device 41 is used to this end. This monitoring device 41 measures or monitors using reflected light technology and is utilizes to determine one or more of the following; whether the filter components are complete, whether the position of the filter components is correct, whether the length of the individual components is correct and, optionally, whether deviations in brightness of individual filter components can be detected. The details of the first monitoring device 41 is described with reference to FIGS. 2-4.

The cut tobacco rod/filter element/cut tobacco rod sections assembled accordingly are then transferred to a feed drum 22 in order to be pushed together in an alignment drum 23. A tipping paper strip 52 drawn off from a tipping paper bobbin 50 or 51 is glued by a gluing device, and then cut into tipping webs in a cutting device 53 on a cutter drum 54 by the knives of a knife drum 53. The severed tipping webs are adhered to the cigarette/filter/cigarette groups on the alignment drum 23 and rolled around the cigarette filter groups on a roller drum 24. A rolling hand 23 and an accelerating element 26 connected thereto accordingly are used to this end in a known manner.

The finished double filter cigarettes are fed to a cutter drum 29 via a transfer drum 28 or a drying drum 28, and are finished to form individual filter cigarettes on this cutter drum by a central cut through the filter plugs. The individual filter cigarettes are then transferred to a transfer drum 31. Another measuring device 42 is provided on this transfer drum 31. This measuring device 42 can also be provided in this transfer drum 31. The measuring device 42 detects, using a reflected-eight method, one or more of the following; whether the tipping paper edge is in the correct position and whether the tipping paper imprint has been made correctly.

Reference is also made to the description below with regard to how these measurements can be carried out.

Subsequently, a turning drum 32 turns a filter cigarette row, and at the same time, transfers it to the unturned filter cigarette row running through. The filter cigarettes reach an ejecting drum 34 via a testing drum 33 that is described, e.g., in DE 35 17 155 C2 of (which U.S. Pat. No. 4,662,214 is a U.S. patent family member). A third monitoring device 43 is located on the ejecting drum 34 (and/or at least partially in the ejecting drum 34). This monitoring device 43 can, for example, monitor the side of the cigarette facing away from the second monitoring device 42 for defects, tears, or other types of general quality features.

Subsequently, the filter cigarettes reach a transfer drum 36 and a blow out drum 37. Certain cigarettes can then be removed as samples by way of a removal drum 38. The filter cigarettes not removed reach a distributing drum 39, which places the filter cigarettes on a distribution belt in a known manner in order to produce a mass flow of filter cigarettes. The production of a mass flow and a corresponding device in this regard is described, e.g., in EP 0 692 201.

FIG. 2 shows a diagrammatic representation of a gradient-index lens 60. In a gradient-index lens 60, the refraction index is embodied to be different or varying crosswise to the optical axis. This is indicated by different gray shadings in FIG. 2. A lens effect is produced by the refraction indices differing from one another crosswise to the optical axis. For this reason, as is shown in the exemplary embodiment from FIG. 2, light beams 61 are focused in a focus 62 on passing through the gradient-index lens 60. The focus 62 can be relatively close to one end of the gradient-index lens. This focus can also be adjusted so that it is arranged precisely on or at an end surface of the gradient-index lens 60. If then, for example, a surface of a cigarette or the surface of a cigarette filter is arranged in or at the focus 62, there can remain little space available between the gradient-index lens 60 and the surface of the cigarette. As a result, there is less distance for material to stay or enter between these two elements, which can lead to less interference in the measuring or monitoring of the respective products. Moreover, an air flow curtain can be used to hold back most or all of the interfering material in this small space.

In order to measure effectively and quickly products extending in a longitudinal axis, such as, e.g., rod-shaped or strip-shaped objects (e.g., cigarettes in the filter tipping machine, glue application and a stamp imprint on paper webs and the like), it is preferred to use a lens arrangement 63, an example of which is shown in FIG. 3. FIG. 3 shows a lens arrangements 63 diagrammatically and opened up in a three-dimensional manner, which lens arrangements comprises an array of gradient-index lenses 60 arranged within a housing. Within the scope of the invention, the term row can be used interchangeably with the term array. In this case, a double row of gradient-index lenses 60 is shown in the arrangement 63.

FIG. 4 shows a corresponding measuring apparatus or monitoring apparatus in a sectional representation. The apparatus utilizes two devices for optical monitoring, each comprising a gradient-index lens 60, and these are utilizes to record an image of a quarter surface of a cigarette filter 64. The apparatus also utilizes two gradient-index lenses 60' that focus the light from a respective light-emitting diode line 66 on the point on the cigarettes 64 of which an image is to be recorded. The corresponding light paths or light beams 61 between these devices are illustrated.

In the arrangement of FIG. 4, in which the cigarettes 64 move in the arrow direction past the monitoring point or the measuring point (i.e., in a transverse axial manner or transversely to the longitudinal axis of the cigarettes 64), only half of the cigarettes 64 are optically monitored. The other half can be monitored at another point. This can be the case, for example, when the cigarettes 64 are arranged the other way around in a groove of a receiving drum. Te CCD lines used in FIG. 4 record accordingly the area to be monitored, i.e., the desired surface of the cigarettes 64. Moreover, a computer 70 (see FIG. 1) is utilized to compare the recorded image with a predetermined and/or stored image. The stored image can represent the desired condition of the surface of the cigarettes 64. If the recorded image that was obtained by the respective CCD line 65 corresponds to the stored image or deviates therefrom within a corresponding tolerance range, the cigarette 64 is allowed to be conveyed further normally in the machine, e.g., according to FIG. 1. If the optical monitoring detects that the cigarette 64 is faulty in some way, this cigarette 64 can be discharged, e.g., in the removal drum 38. This can occur by the computer 70 generating a signal which causes cigarette 64 to be discharged. The computer 70 can be electrically connected to the various monitoring devices 41-43 as is indicated by dotted lines in FIG. 1.

The invention also provides a compact optical inspection system with high optical resolution. In particular, the surface of an object can be imaged with a row of gradient-index lenses on a line of photodiodes or a CCD line. The illumination of the object surface is also preferably carried out with a row of gradient-index lenses. The use of this compact optical surface inspection system or the compact optical monitoring system for cigarettes, filter machines, and filter tipping machines, is advantageous because of the compact construction

The imaging is not carrion out by conventional lens systems, but by, e.g., lining-up gradient-index lenses on a line of photodiodes or a CCD line. Apart from the compact construction, the high optical quality and resolution is advantageous and the fact that the gradient-index lens lines can be lined up in a modular manner is as well. Particles flying around that could otherwise influence the monitoring result can be held back by a small barrier air curtain due to the proximity of the object or product surface to the gradient-index lens or tens row, which can be arranged in the range of a few millimeters or very close to the object or product surface. The illumination can also be integrated into the optical monitoring device in a compact manner through an LED row that is arranged parallel to the detector diode line. The light produced by the LED line can be focused on the object surface by a line or row of gradient-index lenses.

It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.

List of Reference Numbers  1 Filter tipping machine  2 Transfer drum  3 Cut tobacco rod cutter drum  4 Spreader drum  5 Feed drum  6 Cutter drum  7 Staggering drum  8 Pusher and cutter drum 10 Circular knife 11 Pusher drum 12 Accelerating drum 13 Accelerating drum 15 Cutter drum 16 Staggering drum 17 Pusher and cutter drum 18 Staggering drum 19 Staggering drum 21 Transfer drum 22 Feed drum 23 Alignment drum 24 Roller drum 26 Acceleration element 27 Rolling hand 28 Transfer drum 29 Cutter drum 31 Transfer drum 32 Turning drum 33 Testing drum 34 Ejecting drum 36 Transfer drum 37 Blow out drum 38 Removal drum 39 Distributing drum 41 1^(st) monitoring device 42 2^(nd) monitoring device 43 3^(rd) monitoring device 50 Bobbin 51 Bobbin 52 Tipping paper 53 Tipping paper cutter 54 Tipping paper drum 60, 60′ Gradient-index lens 61 Light beam 62 Focus 63 Lens element 64 Cigarette 65 CCD line 66 Light-emitting diode line 70 Computer 

1. A method comprising: optically monitoring a tobacco-processing industry product with a gradient-index lens.
 2. The method of claim 1, wherein the gradient-index lens is arranged on a machine for making a tobacco product.
 3. The method of claim 1, wherein the gradient-index lens comprises a plurality of gradient-index lenses arranged at least one of next to one another and in at least one row.
 4. The method of claim 3, wherein the plurality of gradient-index lenses are structured and arranged to illuminate a surface of the tobacco-processing industry product.
 5. The method of claim 1, wherein the gradient-index lens is structured and arranged to illuminate a surface of the tobacco-processing industry product.
 6. The method of claim 1, further comprising a plurality of other gradient-index lenses arranged at least one of next to one another and in at least one row.
 7. The method of claim 6, wherein the plurality of other gradient-index lenses are structured and arranged to illuminate a surface of the tobacco-processing industry product.
 8. A device for optically monitoring tobacco-processing industry products, the device comprising: an image-recording device comprising at least one gradient-index lens.
 9. The device claim 8, wherein the at least one gradient-index lens is arranged on a machine for making a tobacco product.
 10. The device of claim 8, wherein the at least one gradient-index lens comprises a plurality of gradient-index lenses arranged at least one of next to one another and in a row.
 11. The device of claim 8, wherein the image-recording device further comprises one of a line of photodiodes and a CCD line.
 12. The device of claim 8, wherein the image-recording device comprises at least one of a photodiode and a CCD.
 13. The device of claim 8, wherein the image-recording device further comprises a device for comparing a recorded image with at least one predetermined image.
 14. The device of claim 8, further comprising a device for comparing a recorded image recorded by the image-recording device with at least one predetermined image.
 15. The device of claim 8, further comprising an illumination device for illuminating an object surface.
 16. The device of claim 15, wherein the illumination device illuminates the object surface using a light source and at least one gradient-index lens guiding light from the light source to the object surface.
 17. The device of claim 16, wherein the image-recording device records an image of the object surface that is illuminated by the illumination device.
 18. The device of claim 17, further comprising a plurality of gradient-index lenses arranged at least one of next to one another and in a row.
 19. The device of claim 8, further comprising a plurality of other gradient-index lenses arranged at least one of next to one another and in a row to illuminate an object's surface.
 20. The device of claim 8, wherein the image-recording device comprises at least one gradient-index lens, and wherein a focus of the at least one gradient-index lens is arranged at or on an object surface.
 21. The device of claim 20, wherein the focus is arranged one of: at one end of the at least one gradient-index lens; and in an immediate proximity of one end of the at least one gradient-index lens.
 22. A machine for making tobacco-processing industry products, the machine comprising: a device for optically monitoring products of the tobacco-processing industry comprising a gradient-index lens.
 23. The machine of claim 22, wherein the tobacco-processing industry products comprise one of filter rods and cigarettes.
 24. The machine of claim 22, wherein the tobacco-processing industry products are guided in a transverse axial manner past a device for optical monitoring of products.
 25. The machine of claim 24, wherein the at least one gradient-index lens comprises a plurality of gradient-index lenses arranged at least one of next to one another and in at least one row.
 26. A method of optically monitoring a product in a machine for making or processing tobacco-processing industry products, the method comprising: arranging a device for optical monitoring of the product on the machine for making or processing tobacco-processing industry products, wherein the device for optical monitoring comprises at least one gradient-index lens. 